Increasing circuit density has not only improved the complexity and performance of integrated circuit devices but also has provided lower cost parts to consumers. With decreasing feature sizes and increasing current density in semiconductor devices, the resilience of interconnect structures in the devices to damages caused by electromigration also decreases. Therefore, electromigration characteristics have become one of the key indicators for characterizing the reliability of semiconductor devices.
In a semiconductor logic circuit device, the copper interconnect structure can have from a few to several tens of conductive layers, which are interposed between interlayer dielectric layers made of a material having a low dielectric constant. The number of the copper layers corresponds to the number of interlayer dielectric layers disposed between the copper layer metal interconnect structure. Due to the low mechanical strength of low dielectric constant materials and the poor adhesion between the copper and the etch stop layers disposed in the copper interconnect structure, the etch stop layer and the copper layer in the copper interconnect structure is prone to delamination that results in a diffusion of copper into the interlayer dielectric layer, thereby causing an increase in electromigration and a substantial drop in electrical properties of the semiconductor device.
Thus, there is a need for a method and device to solve the above problems.